Drill bit



D. P. WORTH Sept. 3, 1963 DRILL BIT Filed April 13, 1959 3 SheetsShee c 1 INVENTOR. D. P. W0 RTH A TTOR/VEY'S Sept. 3, 1963 D. P. WORTH 3,102,601

DRILL BIT Filed April 13, 1959 3 Sheets-Sheet 2 FIG. 2

INVENTOR. D. P. WORTH A TTORNEKS 3,1tl2,601 DRILLBIT Daniel P. Worth, Bartlesvilie, Okla assignor to Phillips Petroleum Company, a corporation of Delaware Filed Apr. 13, 1959, Ser. No. 806,016 9 Claims. (Cl. 175-339) This invention relates to improvements in drill bits, particularly in rotary drill bits having at least two cutters or cutter cones such as the type of rotary bits used in drilling wells. Specifically, the improvements relate to providing such a drill bit having therein means for releasing drilling fluid at and for predetermined intervals from the face of a tooth on the cutter in order to thereby blow the detritus broken loose from the formation away-from the cutter. It is preferred to use a compressed gas such as air for the drilling fluid that is released from the face of the tooth, but grit-free liquids may also be used.

Prior art drill bits of this nature have been concerned with the problems of removing the detritus efliciently from the region where it is broken away from the parent formation. One reason it is desirable to remove the detritus is to avoid regrinding the same because such regrinding causes an unnecessary waste of energy and undesirable wear on the cutter. Accordingly, the prior art has provided a large number of arrangements to direct drilling mud of various compositions into the general region of drilling. However, all of these arrangements rely on flooding the general area of the drilling action with suflicient fluid to wash away the detritus. These various arrangements all rely on more or less random motion and circulation of the fluid around and over the cones or cutters in order to achieve the desired detritus removal.

The instant invention improves on all of these various arrangements by directing a stream of drilling fluid, e.g., compressed gas or air, directly behind the detritus, or chip, as the latter is broken away from the formation. By admitting the drilling fluid behind the chip and at the proper time it is possible to push the chip away from the cutting member and away from the immediate region of cutting, to thereby leave a relatively clean work surface, and thus avoiding regrinding and also preventing balling of the chips on the surfaces of the cutter itself.

In one specific embodiment this action is accomplished by directing drilling fluid through appropriate passageways of the structure that supports the cutter. When the cutter reaches a certain position with relation to the formation being drilled, drilling fluid flows through these passageways, then through a passage in the cutter to the face of a tooth in the cutter that is in contact with the detritus. The action is then such as'to blow the detritus clear of the cutter. The flow of drilling fluid from the face of the tooth is maintained for a predetermined time. Accordingly, it is an object-of this invention to provide an improved drill bit. It is also an object to provide meansin a drill bit for the timed release of drilling fluid behind a chip broken away from the formation. It is an object of this invention to provide, such an improved United States Patent v H aisasai Patented Sept. 3, 1%63 invention.

Throughout the drawings the same numbers are used to refer to the same elements.

The essence of the instant apparatus is to provide a rotary drill bit which will emit drilling fluid at a point behind a chip at about the time that chip is removed from its parent formation. In order to do this, appropriate means are provided for conducting the drill-ing fluid through various portions of the drill bit to a point immediately behind the chip, or detritus. Moreover, these means include structure-that permits maintaining the flow of this drilling fluid for a predetermined time in order to assure removal of the chip from the cutting area.

To facilitate an understanding .of the construction and operation of this invention reference is first made to FIG- URE 6 which shows in partial cross-section a toothed cutter 10 that is rotatably mounted on a hollow spindle 11. The cutter 10 preferably comprises a body with a conical external surface and a plurality of teeth protruding from. the external surface. A fluid course comprising axial passage 12' and radial passage 13 is disposed within the spindle for conveying therethrough drilling fluid, preferably compressed air, from a source of supply such as a compressor (not shown). Protmding from the cutter 10 area plurality of teeth 14 having thereon an active face 15. By an active face I refer. to the face of the tooth that is facing towards the chip or detritus '17 that breaks away from the parent formation 19. One end of another fluid course 21 (cutterfluid course) is disposed in the active face. The fluid course 21 extends through the body of the cutter to the bearing recess 22 that is centrally disposed within the cutter. A timing slot 23 provides means for the two fluid courses. to communicate with each other for a predetermined time. The timing slot can be disposed in either the spindle 11 (FIG- URE 6) or the bearing recess 22 (FIGURE 5) of the cutter. I 1

In operation, assume that the drilling rig associated with the rotary bit of FIGURE 6 rotates to move the center of spindle 12 in the direction indicated by the arrow 26. This will cause the cutter 10 to rot-ate relative to the spindle 11 in the direction shown by the arrow 27. In the course of events, the bottom-most tooth 14 is forced into engagement with the formation 19. As rotation continues a sort of prying, chiseling action takes place that drives the tooth 14 into the formation 19 and pries loose a chip 17. At a predetermined point in the rotation cycle of the cutter relative to .the spindle, one

i of the cutter fluid courses 21 comes into communicadrill bit which is particularly adapted for the timedre tion with the timing slot 23. At this time compressed gas (which is used herein by way of example, not limitation) moves through the fluid course 12, 13 in the spindle, through the timing slot 23, and through the cutter fluid course 21, exits from the active face of the tooth, and blows the chip 17 away from the .toothand out of the region of drilling in theformation (work place). The compressed gas or other drilling fluid continues to be emitted from the active face of the tooth until such time as the cutter body rotates to a position where the cutter fluid course v21 is no longer in communication with the timing slot 23. It should be apparent that the function of the timing slot is to maintain a flow of drilling fluid for a predetermined time during the working cycle of the path of rotation of the tooth 14 wherein such a tooth is in cutting contact with the formation 19 and in chipremoving contact with the detritus 17. Similarly, when I use the term rotation cycle in the instant disclosure in claims I refer to a 360 movement of the tooth 14 about the spindle 1'1.

It should'tnow be apparent that I have provided an ap paratus that will emit drilling fluid from the active face of a rotary cutter in-a position behind a chip to thereby blow the chipaway from the next succeeding cutter and to prepare the work area of the formation being cut for the next cutting operation.

In FIGURES 1 and 2 are shown structural details of the manner in which the cutter, or cutter cone, and the spindle are assembled. The assembly of the cone andspindle 11 is supported from a bit leg or shank 30. The spindle can either be welded to the shank or can be forged integrally therewith. The base of the cutter, i.e., that end of the cutter which is disposed'adjacent the shank, is denoted by numeral 31 (see FIGURE 2). That portion of the shank that is vertically below the extended dimensions of the spindle is termed the shirt tail and is denoted as 32 in the figures. The shirt tail provides a shield or cover for the base of the cutter. Formed integrally with the shank 30 is the shroud 33 that protects and shields the upper end of the cutter base. It is common practice to dispose jets for drilling mud within the shroud. Unless otherwise referred to specifically, the term shank will be used to refer to the shirt tail 32, the shroud 33, and their associated structure. The associated structure includes the threaded pin 34 and the extension 36, through the shank, of the spindle fluid course 12. The pin is used for securing the shank to a similarly threaded box in the drill collar of a string .of drill pipe which is in turn attached to a rotary rig, which latter is disposed to the surface of the earth.

Ordinarily, a plurality of two or more of the cutter cones are mounted in the fashion shown in FIGURES 1 and 2 to one unit. That is, from the pin 34 depends two or three shanks 30 which in turn each support a cutter cone. If desired, the fluid course through the shank can include the passageway 38 which extends through the shirt tail and to the surface of the shirt tail that is adjacent the base 31. In this manner fluid can be delivered to the row of teeth adjacent the base of the cutter without having to go through a fluid course in the spindle .11.

The bearing arrangement includes bearings for both the radial and the thrust loads relative to the spindle 11. The radial loads are carried by the outboard bearings 40 and the inboard bearings'42. The former are shown as ball-bearings but may also be roller or journal bearings and are provided with suitable conventional spacers or retainers 41. The inboard radial bearing comprises the roller bearings 42 spaced apart by the retainer 43. In some installations it may be possible to omit the spacers 41 and 43. In order to economize on the space requirements for these hearings, the periphery of shaft :11 and selected inner portions of the bearing 4 retaining the cutter inits position relative to the spindle 1 1 by the co-action of the balls 48 with the groove 52. A plug 54 completes the assembly. Plug 54 is pressfitted into the cutter 10 and is designed as shown in FIGURE 3.

FIGURE 3 shows the details of this plug. A key 56 having the wedge shaped construction of this figure is formed as part of the plug. The plug also has first and second heads 57 and 58, the upper one of which is removed after the assembly operations discussed below have been completed.

FIGURES 4 and 5 show other embodiments of apparatus generally similar to that of FIGURES 1, 2 and 6 which have already been described. The principal difference is, that in FIGURES 4 and 5 the timing slots 23 are formed 'in the cutter cone. FIGURE 4 shows the timing slot 23 as formed in the cutter cone base where fluid can be transmitted thereto from the shirt-tail fluid course 38. FIGURE 5 shows the timing slot formed into the bearing recess 22. The embodiment of FIG- URE 5 is preferred from a structural strength standpoint because it removes less material from the diameter of the spindle, and therefore provides the latter with greater beam strength through a given diameter than does, for

example the species-of FIGURE 6. FIGURES 4 and 5 also show that the invention need not be applied to direct fluid to the active face of each and every tooth on a cutter cone. This would be especially true in the smaller sizes of rotary bits. FIGURE 6, on the other hand, shows that not only can fluid courses be directed to the active face of every tooth, but even that a secondary or cleanup stream of drilling fluid or compressed air can be admitted at and for timed intervals from fluid courses denoted as 60' which are disposed between respective adjacent ones of the teeth 14.

In design and manufacture of the invention as described herein, it is preferred that any fluid courses 12 that pass through the spindle :be located centrally thereof in order to maximize the beam strength of the same. Generous fillets and rounded corners should be provided wherever possible. The hole for the plug 54 and respective fluid courses shown in the various drawings can be formed by cores during casting of the cone or by drilling along the center lines of the various paths shown;

recess 22 of the cutter cone comprise the inner and outer ferred that the outboard thrust collar 46 have a press fit onto the spindle 11 and that the in-board thrust collar 49 be pressor shrunk-fitted to the shaft 11. The balls 48 are held by retainer 47 in retaining engagement with a retaining groove 52 which is formed in the countour of the bearing recess22. This unique engagement permits where internal angular fluid courses are illustrated it is of course necessary to drill two holes. For example, the L-shaped holes in the cutter cone should be drilled from the outside of the tooth in toward the bearing recess, plugged at the tooth, and then drilled from the active face of the tooth into the first passage drilled. Internal burrs, scratches and/or core material can be removed by pumping an abrasive-containing fluid through the various fluid courses at a high velocity.

The assembly procedure is complicated due to the fact that balls 48 perform a retaining function as well as a thrust bearing function. In doing this the balls 48 protrude out past the races between which they are disposed. The shank and cone, as well as the bearings, should all be formed beforehand with the shank and cone having all the necessary air passages and slots machined therein. Then the hole for plug 54 is machined to size in the cone at the place where the plug is to be placed. A plug formed as shown in FIGURE 3 is now expansionor press-fitted into the cone. Now the retaining groove 52 in the cone in which the balls 48 travel is machined. In this manner, the end of the plug 54 is contoured to mate with the balls 48. The plug is now removed by grasping it under the outer-most head and removing it. 'Now, the bearing 40 is positioned within the cone. Assemble the other bearing 42 and the in-board thrust collar 49 on the spindle 11 and then place the cone upon the shaft until the races 46 and 49 are almost finally disposed with respect to each other. At this time the balls 48 are inserted through the hole borehole, thus reducing the where the plug 54 goes. The retainer 47 being in position, the balls will be properly spaced with respect to each other and with respect to the shaft. When this operation is complete the cone is pressed to move the collar 46 the rest of the way onto the shaft. In this manner the contours of the races 46 and 49 that match the balls 52 will not interfere with the emplacement of the latter. The plug can now again be press fitted into place and the outer-most head 58 can be cut ofl and milled or ground flush with the surface with the cone. The wedge-shape of the key 56 on the plug facilitates its proper alignment upon this second press-fit. P-ress, expansion or shrink, fits can be used, the latter two methods as by heating and cooling certain parts, as is well known to those skilled in the art.

It is preferred to use a compressed gas as the drilling fluid which is released from the face of the tooth. Other gases may be desirable, particularly non-combustible ones such as nitrogen and carbon dioxide. Two advantages are realized from using a compressed gas: lubricant can be introduced thereinto at the surface of the earth and delivered to the drill bit bearings (the cone could even provide bleed passages to leak such gas-lubricant through the bearing area), and the gas will aerate any conventional liquid drilling fluid that is present in the effective or apparent liquid density and therefore reducing bottom-hole liquid pressures.

It is contemplated that conventional liquid drilling fluids (muds) be used in conjunction with the instant apparatus, by introducing such muds through the shank in the general vicinity of the shroud 33. This is the conventional mode of delivering mud to the bottom of the borehole. By employing a suflicient quantity of such mud, the detritus is carried out of the borehole or will after having been pushed away from the cutter tooth by the action described above.

Liquid drilling fluid can also be passed through the various fluid courses in lieu of compressed gas. Where this is the case, the mud must be carefully filtered to remove grit and dirt so the bearings can operate freely. In such case, it is preferred to use a liquid of substantially the same composition as that mentioned in the immediate preceding paragraph. In some instances it may be necessary to employ additives to reduce the viscosity of the liquid in order to avoid excessive pressure drop as the liquid passes through the various fluid courses. Again, if liquid is used here, it is also contemplated that an additional volume of liquid be supplied through the shroud, as above mentioned, and in a quantity suflicient to carry the detritus out of the well.

It is believed evident that the foregoing disclosure adequately teaches the mode of operation, construction, and advantages of my invention. It is not my intention to be limited to the precise structure shown in the drawings, but to include all the equivalents thereof. For example, it is not absolutely necessary to use the hearing arrangement I have shown because other bearing arrangements which are known to those skilled in the art could be substituted therefor. It is within the spirit and scope of my invention to include all those modifications, variations, and changes which will be obvious to one skilled in the art with the above disclosure before him.

I claim:

1. In a drill bit that includes a combination of a shank, a spindle secured to said shank, a cutter rotatably mounted on said spindle, means for securing said cutter against motion axially of said spindle, said cutter having a tooth with an active face and a bearing recess for receiving said spindle; the improvement comprising a first fluid course extending through said shank and axially of said spindle and terminating at the circumference of said spindle; a second fluid course extending through said cutter from said active face on said tooth to said bearing recess, said second fluid course terminating in that portion of said active face that is brought into direct contact with the detritus, said first and second fluid courses terminating at the spindle circumference and in the bearing recess, respectively, for communication with each other during the working cycle of said cutter.

2. In a drill bit that includes the combination of a shank, a spindle secured to said shank, a cutter rotatably mounted on said spindle, means for securing said cutter against motion axially of said spindle, said cutter having a plurality of teeth and a bearing recess for receiving said spindle with each of said teeth having an active face; the improvement comprising a first fluid course extending through said shank and axially of said spindle and terminating at the circumference of said spindle; a second fluid course extending through said cutter from said active face on one of said teeth to said bearing recess, said second fluid course terminating in that portion of said active face that is brought into direct contact with the detritus; and a third fluid course extending through said cutter from between two teeth on the surface of said cutter to said bearing recess, said first and second fluid courses terminating at the spindle circumference and the bearing recess, respectively, for communication With each other during the working cycle of said cutter, said first and third fluid courses terminating at the spindle circumference and in the bearing recess, respectively, for communication with each other during a part of the rotation cycle of said cutter.

3. In a drill bit that includes a combination of a shank, a spindle secured to said shank, a cutter rotatably mounted on said spindle, means for securing said cutter against motion axially of said spindle, said cutter having a tooth with an' active surface and having a base at that end of itself which is disposed adjacent said shank, said shank having a surface adjacent to and covering said base; the improvement comprising a first fluid course extending through said shank to said surface; another fluid course extending through said cutter from said active face on said tooth to said cutter base, said another fluid course terminating in that portion of said active face that is brought into direct contact with the detritus; said fluid course and said another fluid course being-at the same radius from the axis of said spindle where they terminate, respectively, at the shank surface and cutter base for communication with each other during the working cycle of said cutter.

4. A drill bit according to claim 1 further comprising a circumferentially extending timing slot disposed in said spindle in communication with said first fluid course and of a circumferential length to effect communication between said first and second fluid courses during the working cycle of said cutter.

5. A drill bit according to claim 1 further comprising a circumferentially extending timing slot disposed in said bearing recess in communication with said second fluid course and of a circumferential length to effect communication between said first and second fluid courses during the working cycle of said cutter.

6. A drill bit according to claim 1 wherein that portion of said second fluid course which terminates at said active face is substantially perpendicular to said active face.

7. A drill bit according to claim 2 further comprising a circumferentially extending timing slot disposed in said spindle in communication with said first fluid course and of a circumferential length to effect communication between said first and second fluid courses and between said first and third fluid courses during the working cycle and for a predetermined part ofa rotation cycle, respectively, of said cutter.

8. A drill bit according to claim 3 further comprising timing slot means disposed in said shank surface in communication with said fluid course where said fluid course terminates in said shank surface for maintaining the said respective fluid courses in communication during the working cycle of said cutter.

9. A drill bit according to claim 3 further comprising a timing slot means disposed in said cutter base in com- References Cited in the file of this patent UNITED STATES PATENTS 

1. IN A DRILL BIT THAT INCLUDES A COMBINATION OF A SHANK, A SPINDLE SECURED TO SAID SHANK, A CUTTER ROTATABLY MOUNTED ON SAID SPINDLE, MEANS FOR SECURING SAID CUTTER AGAINST MOTION AXIALLY OF SAID SPINDLE, SAID CUTTER HAVING A TOOTH WITH AN ACTIVE FACE AND A BEARING RECESS FOR RECEIVING SAID SPINDLE; THE IMPROVEMENT COMPRISING A FIRST FLUID COURSE EXTENDING THROUGH SAID SHANK AND AXIALLY OF SAID SPINDLE AND TERMINATING AT THE CIRCUMFERENCE OF SAID SPINDLE; A SECOND FLUID COURSE EXTENDING THROUGH SAID CUTTER FROM SAID ACTIVE FACE ON SAID TOOTH TO SAID BEARING RECESS, SAID SECOND FLUID COURSE TERMINATING IN THAT PORTION OF SAID ACTIVE FACE THAT IS BROUGHT INTO DIRECT CONTACT WITH THE DETRITUS, SAID FIRST AND SECOND FLUID COURSES TERMINATING AT THE SPINDLE CIRCUMFERENCE AND IN THE BEARING RECESS, RESPECTIVELY, FOR COMMUNICATION WITH EACH OTHER DURING THE WORKING CYCLE OF SAID CUTTER. 